Combines are large self-propelled vehicles used for harvesting and threshing agricultural crop in the field. A harvesting head is typically disposed across the front of the combine vehicle supported on a feederhouse. This harvesting head is configured to cut and convey the crop into the combine vehicle itself where it is threshed, separated, and cleaned.
Traditional harvesting heads included an elongate rigid frame to which harvesting implements are added such as cutter bars, augers, reels, and endless belt conveyors. More recently, the once rigid frame has been replaced by multiple frame sections that are coupled together to pivot with respect to each other.
A typical arrangement has a center frame and left and right wing frames that are coupled to the center frame to pivot with respect to the center frame. This arrangement requires that the other elements in the harvesting head also be pivotable with respect to each other. This multiple pivoting frame arrangement permits wider harvesting heads to more accurately follow the contours of the ground as they are harvesting and therefore to cut more crop.
One problem with larger harvesting heads with pivoting frames is their susceptibility to damage. The newer draper frames are longer than traditional frames. They are made lighter per unit length in order to limit their weight. As a result, if they hit obstructions in the field, they are more prone to damage, particularly at the pivot joints where the impact forces are highly concentrated.
This multiple frame arrangement is employed in harvesting heads that use endless belt conveyors to convey material. Such harvesting heads are commonly called “draper platforms”. As the frame sections pivot with respect to each other the conveyor belts can change their tension or alignment and be damaged. The conveyor belts can also rub against other components.
Many devices exist to prevent damage to agricultural equipment driven through agricultural fields planting, harvesting or cultivating crops.
GB 2264619 shows a breakaway shank for a spade mounted on a rectangular toolbar. The upper end of the shank clamps to the toolbar. When an overload condition exists, a bolt breaks due to excessive tensile load and the clamp halves spread apart. This permits the spade to rotate rearwardly, away from the ground around the longitudinally extending toolbar. The spade rotates about a horizontal and laterally extending axis and may even fall off the rectangular toolbar. The toolbar does not breakaway. Instead, individual implements (the spade) mounted on the toolbar break away.
U.S. Pat. No. 5,957,216 shows an arrangement for a lightweight marker boom. It has a resettable breakaway coupling for a laterally extending boom that supports a disc marker for disc marking the field. The boom has a spring loaded detent that permits the boom, when hit with an obstruction, to pivot rearward about a generally vertical axis. The implement-carrying toolbar itself is not configured to break away, just the slender marker boom.
U.S. Pat. No. 4,829,957 shows another arrangement for a lightweight marker boom. It has a breakaway coupling for a lightweight boom supporting a row marker at the end of a planter.
In the above examples, the toolbar carrying the working implements does not break away. The implements do, or the lightweight marker boom does.
U.S. Pat. No. 6,675,668 shows a frame for a multi-section draper platform having three frame sections (five in FIG. 12). It requires an array of linkages and load-balancing elements that extend across the three sections. Pivot pins couple the wing frames to the center frame sections. No means for breaking the toolbar or frame of the draper platform is provided.
DE 102006022480 shows a forage harvester having a header with a center frame section, and with two wing frame sections that are foldable to a transport position. Unlike the above examples, the frame is hinged for transport. The hinge pin coupling the sections can be sheared under high loads permitting the wing frame sections to breakaway when the wings are in their extended operating position. When the hinge pin is sheared no means is described or illustrated to support the wing section and prevent it from falling on the ground and being dragged behind the vehicle.
None of the examples above solve the problem of a draper platform with an implement-carrying frame that can yield to impact, yet is strong enough to support the yielded draper section together with its many components.
This problem is solved by the arrangement described in claim 1. Further advantages are provided by additional claims dependent upon claim 1.